I am interested in comparing two surveys and how well they predict
attitudes toward an advertisement. I know that the standard way to
compare these would be to compare the two correlations (survey 1 with
advertisement rating and survey 2 with the advertisement rating) with
the winner being the survey with the highest r.

However, I am interested in looking at this using ANOVA and trend
tests. I am interested in knowing which survey has the strongest
trend. How could I compare the two tests using the trend methodology?
Is there a number, like r that I can use to compare the two trends?
I'd also be interested in reading more about trend tests and how they
work if you can point me in the right direction.